Image display element and manufacturing method thereof

ABSTRACT

An image display element includes: a front panel; a back panel opposite thereto; a plurality of pixels arranged between both the panels; and plural electrodes for controlling the pixels. The panels are bonded with the pixels and the electrodes interposed therebetween, and the electrodes are connected to a driving circuit via metal film wires. The back panel is divided so as to expose electrode terminals, and a groove part V-shaped in cross section is formed at the divided portion. The metal film wires are formed on the top surface of the back panel, and the electrode terminals and the metal film wires are connected by a conductive paste coated along the tilt surfaces forming the groove part. Partitions are disposed between the adjacent electrode terminals at the bottom of the groove part.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a large size image display deviceincluding, for example, a large number of liquid crystal display (LCD)panels, plasma display panels (PDP), or electroluminescent (EL) displaypanels, arranged therein. More particularly, it relates to an imagedisplay element forming the device and a manufacturing method thereof.

2. Background Art

For a large size image display device (which is also referred to as alarge size display), in order to implement high performances at a lowcost, there has been adopted the system in which a plurality of flatpanel displays (e.g., LCD panels, PDPs, or EL display panels) as imagedisplay elements (or, display units) are arranged in a matrix.

One example of a conventional image display element forming such a largesize display is shown in FIGS. 13A and 13B.

FIGS. 13A and 13B are views showing a part of the array (2-sheet array)of the image display elements. FIG. 13A is a front view, and FIG. 13B isa side view.

An image display element 30 has a front panel 31 and a back panel 32formed of a glass plate or the like. The front panel 31 and the backpanel 32 are opposed each other with a prescribed distance therebetween,between which a plurality of pixels 33, and a plurality of electrodes(not shown) for controlling them are arranged to form a light emittinglayer (or a liquid crystal layer). Thus, the periphery thereof is sealedwith a seal part 34 with a seal width g1.

When a lead line for applying a voltage to the electrode is led out fromthe periphery of the image display element 30, namely, a joint part 35of the adjacent image display elements 30, the lead-out margin isnecessary. When the spacing Ga between the pixels 33 of the adjacentimage display elements 30 at the joint part 35 is larger than thespacing Gb between pixels in the same image display element, the jointpart 35 becomes noticeable.

Thus, as shown in an enlarged view of FIG. 13B, the back panel 32 isdivided into two parts, and a gap part 36 is provided at the centralpart. A terminal 37 corresponding to the electrode is included at thegap part (which is also simply referred to as a gap) 36. An electrodepin or a lead line 38 as shown is connected to the terminal 37, to beled outside the back panel (see, e.g., JP-A-2001-251571).

With the conventional image display element shown in JP-A-2001-251571,the lead line 38 of the electrode is led out from the gap part 36 formedin the back panel 32. Therefore, this configuration is effective as thestructure for making the joint parts 35 of the image display elements 30less noticeable. However, it is configured such that the lead lines 38are connected to a large number of terminals 37 present in the narrowgap part 36, thereby to be connected to a wiring layer. For this reason,connection with the terminals 37 becomes complicated, and further,unfavorably, the lead-out method is complicated, and the workability isbad.

A conventional image display element shown in JP-A-2008-191502 isprovided in order to solve such a problem.

FIG. 14 is a perspective view showing a configuration of the imagedisplay element shown in JP-A-2008-191502. FIG. 15 is an enlarged viewof an essential part of FIG. 14.

Below, the conventional image display element shown in JP-A-2008-191502will be described.

A large number of the image display elements are arranged in a matrix toform a large screen flat panel display.

Examples of the display device of the image display element include aLCD panel, a PDP, and an EL display panel. Incidentally, the figureshows the image display element as seen from the back thereof.

As shown in FIG. 14, the image display element includes a front panel 21formed of a glass plate or the like, a back panel 22 similarly formed ofa glass plate or the like, and opposed to the front panel 21, aplurality of pixels (not shown) arranged in a matrix between both thepanels, and to be selected to be in a display or non-display state, anda plurality of electrodes (not shown) for controlling the pixels. Boththe panels 21 and 22 are bonded with each other with the pixels and theelectrodes interposed therebetween.

The back panel 22 is divided between two adjacent pixel lines, and a gap23 is formed at the divided portion. In the figure, the gap 23 is shownon an enlarged scale for easy understanding, but an actual gap 23 is aminute gap with, for example, a width of about 0.30 mm.

Further, the pixels are arranged in a matrix. Thus, when a reference ismade to “between pixels”, there are “between transverse pixel rows” and“between longitudinal pixel columns”. However, both inclusive arereferred to as “between two adjacent pixel lines”.

Incidentally, as the back panel 22, the one divided into two parts atthe central part is shown. However, the number of divisions and theposition for division are not limited thereto. The back panel 22 may bedivided into three or more parts, and the position for division may alsobe another position so long as it is between adjacent pixels.

On the front panel 21 side situated at the gap 23, a plurality ofelectrode terminals 24 connected to the electrodes are disposed. Theelectrode terminals 24 are formed of, for example, the same material asthat for the electrodes simultaneously, and are exposed from the gap.

On the other hand, on a back surface 22 a of the back panel 22, (theback side of the opposing surface from the front panel is referred to as“back surface”), and on an end face 22 b which is the end part of thegap 23, metal film wires 25 are formed.

The metal film wires 25 are formed by, for example, thick film printing.To the end parts of the metal film wires 25 on the back surface 22 aside, a connector 26 is connected. The metal film wires 25 are connectedto an external driving control circuit via the connector 26.

The details of the wiring part are shown in FIG. 15. As shown in thefigure, the wiring part is formed by aligning the electrode terminals 24and the metal film wires 25 such that the metal film wires 25 on the endpart 22 b of the back panel 22 are in vertical contact with theelectrode terminals 24 on the front panel 21 side with the back panel 22bonded on the front panel 21. Then, solder 27 is coated on the contactportion with the both panels 21 and 22 being bonded together. Both thepanels are locally heated to melt the solder for bonding.

Whereas, FIG. 16 is a perspective view showing the electrode connectionpart when the electrode terminals 24 have been led out from theperipheral end part of the front panel 21.

The following configuration is shown. The back panel 22 is configured tobe slightly smaller than the front panel 21. Thus, upon superposition ofboth the panels, a step part 21 a is formed at the end part, so that theelectrode terminals 24 are exposed at the step part 21 a. Thus, theelectrode terminals 4 and the metal film wires 25 formed at the end part22 b of the back panel 22 come in contact with each other, and arebonded by soldering.

As described up to this point, the image display element shown inJP-A-2008-191502 includes: a front panel 21; a back panel 22 opposite tothe front panel 21; a plurality of pixels (not shown) arranged in amatrix between both the panels, and to be selected to be in a display ornon-display state; and a plurality of electrodes for controlling thepixels, wherein both the panels are bonded together with the pixels andthe electrodes interposed therebetween. In such an image displayelement, the metal film wires 25 are formed on the back surface and theend face (surface of the end part 22 b) of the back panel 22. Theelectrode terminals 24 corresponding to the metal film wires 25 formedon the end face of the back panel 22, and connected to the electrodesare disposed on the front panel 21 side. Thus, the metal film wires 25formed on the end face 22 b and the electrode terminals 24 are bondedtogether by soldering.

Therefore, as compared with the image display element shown inJP-A-2001-251571, leading out of electrodes is possible with a simplemethod from a narrow space without using an electrode lead line. Thiscancels the expansion of the joint width between the image displayelements. When the image display elements are arrayed to form a largescreen, the image quality is improved by joint shrinkage. Further,leading out of electrode lines is simplified, resulting in a reductionof the cost.

With the conventional image display element shown in JP-A-2008-191502,as shown in FIG. 14, the electrode terminals 24 and the metal film wires25 are connected by direct soldering. This enables the electrodes to beled out from the gap (gap/groove part) 23 formed in the back panel 22.

However, this configuration is effective as the structure for making thejoint parts of the image display elements less noticeable, but, at thegroove part (gap part) in the vicinity of the terminal part occurringaccording to the thickness of the back panel 22, the processing tools(tools for soldering such as heads and needles) are still less likely toreach the soldering part (i.e., the contact part between the electrodeterminal 24 and the metal film wire 25) situated at the recesses of thegap (groove part/gap).

Particularly, a display device decreases in pixel pitch with an increasein resolution. Thus, it is also necessary to narrow the width of the gappart for carrying out lead-out of electrodes according to the decreasein pixel pitch. Accordingly, electrode lead-out processing becomesfurther difficult.

Therefore, the connection reliability between the electrode terminals 24and the metal film wires 25 by soldering becomes a problem.

Further, solder 27 for connecting the electrode terminals 24 and themetal film wires 25 is disposed with a fine interval. For this reason,migration tends to occur between the adjacent electrode terminals,between metal film wires, or between solders, which leads to a problemin the insulation property of the electrode lead-out part.

Further, with the conventional image display element shown in FIG. 16,it is possible to lead out electrodes from the peripheral end part ofthe panel with ease. However, a problem is encountered in the panelshape in the vicinity of the terminal part for disposing the electrodelead line thereon, so that lead-out processing of electrodes becomesdifficult.

Examples of the processing method include soldering, wire bonding, andconnection by a conductive paste or the like. However, at the step partin the vicinity of the terminal part occurring according to thethickness of the back panel 22, processing tools (such as a head) becomeless likely to reach the connection part situated at the recesses of thestep part.

Further, with the conventional image display element, the back panel 22is divided by the gap part 23. This also causes a problem that thestrength is reduced upon concentration of a stress to this portion.

SUMMARY OF THE INVENTION

This invention has been made in order to solve the foregoing problem. Itis an object of the present invention to provide an image displayelement capable of readily undergoing electrode lead-out processing byconfiguring the panel shape in the vicinity of the terminal part of theimage display element in a structure suitable for use of processingtools (i.e., a head of a soldering iron, a needle for conductive pasteinjection, and the like) necessary for electrode lead-out processing,and further, capable of inhibiting short circuit in the electrodelead-out part by expansion or protrusion of a conductive paste even whenthe conductive paste having fluidity is used for the connection betweenthe electrode terminals and the metal film wires, and a manufacturingmethod of the image display element.

In accordance with an aspect of this invention, an image display elementincludes: a front panel; a back panel opposite to the front panel; aplurality of pixels arranged in a matrix between the front panel and theback panel, and to be selected to be in a display or non-display state;and a plurality of electrodes for controlling the pixels, the frontpanel and the back panel being bonded together with the pixels and theelectrodes interposed therebetween, and the electrodes being connectedto a driving circuit via metal film wires.

In such an image display element, the back panel is divided such thatelectrode terminals connected to the electrodes are exposed betweenadjacent plural pixel lines, and a groove part having a shape wider atthe top on the back side of the opposing surface from the front panelthan at the bottom is formed at the divided portion, the metal filmwires are formed on the back side surface of the opposing surface fromthe front panel, the electrode terminals and the metal film wires areconnected by a conductive paste coated along a tilt surface forming thegroove part, and partitions are disposed between the adjacent electrodeterminals at the bottom of the groove part.

Further, another aspect of this invention provides a method formanufacturing an image display element including: a front panel; a backpanel opposite to the front panel; a plurality of pixels arranged in amatrix between the front panel and the back panel, and to be selected tobe in a display or non-display state; and a plurality of electrodes forcontrolling the pixels, the front panel and the back panel being bondedtogether with the pixels and the electrodes interposed therebetween, andthe electrodes being connected to a driving circuit via metal filmwires.

Such a method includes: a first step of dividing the back panel suchthat electrode terminals connected to the electrodes are exposed betweenadjacent plural pixel lines, and forming a groove part having a shapewider at the top on the back side of the opposing surface from the frontpanel than at the bottom at the divided portion; a second step offorming the metal film wires on the back side surface of the opposingsurface from the front panel; a third step of connecting the electrodeterminals and the metal film wires by a conductive paste coated along atilt surface forming the groove part; and a fourth step of disposingpartitions between the adjacent electrode terminals at the bottom of thegroove part.

In accordance with the invention, it becomes possible to implement animage display element capable of readily undergoing electrode lead-outprocessing, and capable of inhibiting short circuit in the electrodelead-out part (connection part between the electrode terminal and themetal film wire) by expansion or protrusion of a conductive paste evenwhen the conductive paste having fluidity is used for the connectionbetween the electrode terminals and the metal film wires, and amanufacturing method thereof.

The foregoing and other object, features, aspects, and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view for illustrating the basic configuration ofan image display element in accordance with Embodiment 1 of the presentinvention;

FIG. 2 is an enlarged cross-sectional view of an essential part of FIG.1;

FIG. 3 is a view showing a state in which the width of a groove part issmaller than the width dimension of a tool;

FIG. 4 is a view showing a state in which the groove part is in a Vshape;

FIG. 5 is a conceptual view for illustrating a characteristic structureof the image display element in accordance with Embodiment 1;

FIG. 6 is a view showing the center lead-out system of electrodes;

FIG. 7 is a view showing the end lead-out system of electrodes;

FIGS. 8A to 8C are each a conceptual view for illustrating acharacteristic structure of an image display element in accordance withEmbodiment 2;

FIG. 9 is a conceptual view for illustrating a characteristic structureof an image display element in accordance with Embodiment 3;

FIG. 10 is a conceptual view for illustrating a characteristic structureof an image display element in accordance with Embodiment 4;

FIG. 11 is a conceptual view of an essential part for illustrating acharacteristic structure of an image display element in accordance withEmbodiment 5;

FIGS. 12A and 12B are each a conceptual view of an essential part forillustrating a characteristic structure of an image display element inaccordance with Embodiment 6;

FIGS. 13A and 13B are views each showing a structure of a conventionalimage display element shown in JP-A-2001-251571;

FIG. 14 is a perspective view showing a structure of a conventionalimage display element shown in JP-A-2008-191502;

FIG. 15 is an enlarged view of an essential part of FIG. 14; and

FIG. 16 is a perspective view showing an electrode connection part whenan electrode terminal has been led out from the peripheral end part of afront panel in the image display element shown in JP-A-2008-191502.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Below, embodiments of the present invention will be described byreference to the accompanying drawings.

Embodiment 1

FIG. 1 is a perspective view for illustrating the basic configuration ofan image display element in accordance with Embodiment 1 of thisinvention, and FIG. 2 is an enlarged cross-sectional view of anessential part of FIG. 1.

A large number of the image display elements are arranged in a matrix,thereby to form a large-size flat-panel display.

As the display devices of the image display elements, for example, LCDpanels, PDPs, and EL display panels are used.

As shown in FIG. 1, the image display element includes a front panel 1formed of a glass plate or the like, a back panel 2 similarly formed ofa glass plate or the like, and opposed to the front panel 1, a pluralityof pixels (not shown) arranged in a matrix between the front panel 1 andthe back panel 2, and to be selected to be in a display or non-displaystate, and a plurality of electrodes (not shown) for controlling thepixels. The front panel 1 and the back panel 2 are bonded with eachother with the pixels and the electrodes interposed therebetween.

The back panel 2 is divided in such a manner as to form a groove part 3having a V shape by cutting using a dicing blade (dicing), or the likebetween the adjacent plural pixel lines.

Incidentally, in the figure, the groove part 3 is shown on an enlargedscale for easy understanding, but in actuality, the groove part 3 is aminute gap.

Further, the pixels are arranged in a matrix. Thus, when a reference ismade to “between pixels”, there are “between transverse pixel rows” and“between longitudinal pixel columns”. However, both inclusive arereferred to as “between two adjacent pixel lines”.

Then, on the front panel 1 side situated at the groove part 3, aplurality of electrode terminals 4 connected to the electrodes arearranged. The electrode terminals 4 are formed of, for example, the samematerial as that for the electrodes simultaneously, and are exposed fromthe groove part 3.

On the other hand, a back surface 2 a of the back panel 2 (the back sideof the opposing surface from the front panel 1) is referred to as “backsurface”. (the same applies hereinafter)

On an end face (tilt surface) 2 b of the back panel 2 forming the groovepart 3, metal film wires 5 of a metal (e.g., Ag) are formed. To the endparts of the metal film wires 5 on the back surface 2 a side, aconnector 6 is connected.

The metal film wires 5 are connected to an external driving circuit viathe connector 6.

Incidentally, the materials for the metal film wires 5 are not limitedto Ag, and common wiring materials may be used. Whereas, the wiringmethod of the metal film wires 5 also has no particular restriction,and, other wiring structures such as FPC may be included between themetal film wires 5 and the connector 6.

The details of the wiring part are shown in FIG. 2. As shown in thefigure, the wiring part is formed by aligning the electrode terminals 4and the metal film wires 5 such that the metal film wires 5 on the tiltsurface 2 b on the end part of the back panel 2 are in contact with theelectrode terminals 4 on the front panel 1 side with the back panel 2bonded on the front panel 1.

Incidentally, the portion of each electrode terminal 4 exposed at thegroove part 3 is covered with each metal film wire 5. As a result, theelectrode terminal 4 is in contact with the metal film wire 5 withreliability.

Further, also in FIG. 1, the portion of each electrode terminal 4exposed at the groove part 3 is entirely covered with each metal filmwire 5.

In FIG. 1, in order to show that the portion of each electrode terminal4 exposed at the groove part 3 is covered with each metal film wire 5,the metal film wire 5 is shown in a partially cut away view.

The back panel 2 is generally formed of glass. For this reason, themetal film wires 5 are formed by coating with thick film printing or thelike, using, for example, a silver (Ag) paste, followed by sintering.

In this case, the processing tools such as needles and heads necessaryfor performing thick film printing or the like are required to be movedin proximity to the end face 2 b of the back panel 2.

Herein, as shown in FIG. 3, when the end face 2 b of the back panel 2 isvertical to the panel surface, and the width of the groove part 3 issmaller than the width dimension of a tool 7, such as a width of thegroove part 3 of 0.30 mm, and a width dimension of the tool 7 of 0.36mm, thick film printing is difficult to properly perform.

In contrast, in Embodiment 1, in the divided portion of the back panel2, the groove part 3 having a V shape wider at the top on the oppositeside of the front panel 1 than at the bottom is formed. Therefore, asshown in FIG. 4, the tool 7 necessary for thick film printing or thelike can be moved in proximity to the end face 2 b of the back panel 2.This enables the metal film wires 5 to be formed with ease andprecision.

Incidentally, in FIG. 2, “g1” denotes the width of the top of the groovepart 3; “g2”, the width of the bottom; and “θ”, the tilt angle of theend part (end face) 2 b of the back panel 2.

In accordance with this invention, as shown in FIGS. 1, 2, and 4, theimage display element includes: the front panel 1; the back panel 2opposite to the front panel 1; the plurality of pixels arranged in amatrix between both the panels (i.e., the front panel 1 and the backpanel 2), and to be selected to be in a display or non-display state;and the plurality of electrodes for controlling the pixels. Both thepanels are bonded together with the pixels and the electrodes interposedtherebetween. In such an image display element, the back panel 2 isdivided in such a manner as to form a groove part having a shape widerat the top on the opposite side of the front panel 1 than at the bottombetween adjacent plural pixel lines. Thus, the metal film wires 5 forconnecting the electrodes to a driving circuit are formed along the endface (tilt surface 2 b) situated at the groove part 3. This enables theelectrodes to be led out from the narrow region of the panel. When aplurality of the image display elements are displayed in a matrix, thewidth of the joint part can be narrowed. As a result, it is possible toimplement a high-resolution image display device with unnoticeable jointparts. In addition, further, it is possible to implement ahigh-reliability image display device capable of improving thereliability of the metal film wires themselves, and inhibiting theoccurrence of migration between the adjacent metal film wires or betweenelectrode terminals, and the like.

Up to this point, the basic configuration and the effects of the imagedisplay element in accordance with the invention were described.However, below, a description will be given to a characteristic specificexample of the image display element in accordance with Embodiment 1.

FIG. 5 is a conceptual view for illustrating the characteristicstructure of the image display element in accordance with Embodiment 1,and shows a case where the electrode terminals 4 and the metal filmwires 5 are connected by coating with a conductive paste (e.g., Agpaste) 10 to be connected.

In the example shown in FIG. 1, the metal film wires 5 for connectingthe electrode terminals 4 to an external driving circuit via theconnector 6 are formed to also cover the region of “the end face 2 b ofthe back panel 2” which is the tilt surface forming the V-shaped groovepart (i.e., the groove part having a shape wider at the top on theopposite side of the front panel 1 than at the bottom) 3 so as to be indirect contact with the end parts of the electrode terminals 4.

Incidentally, the metal film wires 5 are, as described above, formed bycoating, for example, a Ag paste in a thick film, followed by sintering,and are arranged in correspondence with respective electrodes.

In contrast, in FIG. 5, connection between the electrode terminals 4situated at the bottom of the V-shaped groove part 3 and the metal filmwires 5 formed on the back surface 2 a of the back panel 2 isestablished by coating of a conductive paste (e.g., Ag paste) 10therebetween.

Incidentally, the conductive paste 10 is coated on the top surface ofeach electrode terminal 4. However, in order to show this state, in FIG.5, the conductive paste 10 is shown in a partially cutaway view.

In FIGS. 8A to 8C, 9 and 10 described later, the conductive paste 10 isshown in a partially cutaway view for the same reason.

Further, FIG. 5 is drawn as if the end part of each metal film wire 5was in contact with the end part of each conductive paste 10 toestablish connection therebetween. However, in actuality, the conductivepaste 10 is coated even to the top surface of the end part of each metalfilm wire 5. This also applies to FIGS. 8A to 8C, 9 and 10 describedlater.

Wiring by the conductive paste 10 facilitates processing, and control ofthe thickness of the conductive paste 10 is also easy.

This improves the performances (e.g., uniformity of the contactresistance) of the connection part between the electrode terminal 4 andthe metal film wire 5, and the reliability of connection.

However, when a conductive paste (Ag paste) having fluidity is used, theconductive paste 10 coated along the tilt surface 2 b forming the groovepart 3 protrudes or expands at the bottom of the groove part 3, whichmay cause short circuit between the adjacent electrode terminals orbetween the metal film wires.

In other words, it has been difficult to lead out electrodes from thegroove part 3 which is the step part between the front panel 1 and theback panel 2 so as not to cause short circuit between the adjacentelectrode terminals or between the metal film wires.

Thus, in this embodiment, in order to prevent the coated conductivepaste 10 from protruding or expanding at the bottom of the groove part3, thereby causing short circuit between the adjacent electrodeterminals or between the metal film wires, partitions 11 of a resinmaterial or the like are provided between the adjacent electrodeterminals 4.

Incidentally, the partitions 11 can be formed with ease at a low cost byusing a resin material.

As described up to this point, the image display element according tothis embodiment includes: the front panel 1; the back panel 2 oppositeto the front panel 1; a plurality of pixels arranged in a matrix betweenthe front panel 1 and the back panel 2, and to be selected to be in adisplay or non-display state; and a plurality of electrodes forcontrolling the pixels, wherein the front panel 1 and the back panel 2are bonded together with the pixels and the electrodes interposedtherebetween, and the electrodes are connected to a driving circuit viametal film wires 5. In such an image display element, the back panel 2is divided such that electrode terminals 4 connected to the electrodesare exposed between adjacent plural pixel lines. In addition, the groovepart 3 having a shape wider at the top 2 a on the back side of theopposing surface from the front panel 1 than at the bottom is formed atthe divided portion, and the metal film wires 5 are formed on thesurface of the top (i.e., the back side surface 2 a of the opposingsurface from the front panel 1) of the back panel 2. The electrodeterminals 4 and the metal film wires 5 are connected by the conductivepaste 10 coated along the tilt surface forming the groove part 3. At thebottom of the groove part 3, the partitions 11 are formed between theadjacent electrode terminals 4.

This enables the electrodes to be led out from the narrow region of thepanel. As a result, it is possible to implement a high-resolution imagedisplay device with unnoticeable joint parts of the panel with ease. Inaddition, further, it is possible to inhibit short circuit between theadjacent electrode terminals or between the metal film wires due toprotrusion or expansion of the coated conductive paste 10 at the bottomof the groove part 3 even when the conductive paste having fluidity isused.

Incidentally, the foregoing description is intended for the back panel 2divided into two parts at the central part. However, the number ofdivisions and the position for division are not limited thereto. Theback panel 2 may be divided into three or more parts, and the positionfor division may also be another position so long as it is betweenadjacent pixels.

For example, as shown in FIG. 6, the back panel 2 is divided into fourparts by the cross-shaped groove part 3, which is also applicable to thecenter lead-out system in which electrodes are led out from the centerof the image display element.

Further, the back panel 2 is also applicable to the case where theelectrode terminals 4 are led out from the outer peripheral end part ofthe front panel, or the structure of the end part lead-out system inwhich electrodes are led out from both the horizontal and vertical endparts of the image display element as shown in FIG. 7.

This also applies to the image display elements of respectiveembodiments described later.

Embodiment 2

FIGS. 8A to 8C are each a conceptual view for illustrating thecharacteristic structure of an image display element according toEmbodiment 2. FIG. 8A is a conceptual view, and FIG. 8B is a detailedview of an essential part of FIG. 8A.

In this embodiment, as shown in FIGS. 8A to 8C, in the configuration ofFIG. 5 described above, a pit 12 is disposed in the portion of thebottom of the groove part 3 at which the conductive paste 10 isconnected to the electrode terminal 4 so that even when a part of theconductive paste 10 having fluidity runs down to the bottom of thegroove part 3, the running down conductive paste 10 is reserved.

Incidentally, the pit 12 herein referred to denotes, as shown in FIG.8C, the configuration of a concave part 2 d previously formed by spotfacing in the portion corresponding to the divided portion on the sideof the back panel 2 opposite to the front panel 1. The pit 12 is formedat the groove part 3-formed position of the back panel 2 at which eachelectrode terminal 4 is situated.

After the front panel 1 and the back panel 2 are bonded to each other,dicing by a dicing blade 8 is performed from the backside (back surfaceside) of the opposing surface from the front panel 1, thereby to formthe groove part 3. Thus, the electrode terminal 4 is exposed through thepit 12.

The pits 12 are respectively formed at the formation positions of theelectrode terminals 4. This can prevent the coated conductive pastehaving fluidity from protruding or expanding at the bottom of the groovepart 3, and thereby causing short circuit between the adjacent electrodeterminals.

Embodiment 3

FIG. 9 is a conceptual view for illustrating the characteristicstructure of an image display element according to Embodiment 3.

This embodiment has the following feature. As shown in FIG. 9, in theconfiguration of FIG. 5 in Embodiment 1, the partitions 11 (see FIG. 5)of a resin material or the like are not disposed between the adjacentelectrode terminals 4. Instead, a part of the step part of the bottom ofthe tilt surface 2 b forming the groove part 3 is formed in an unevensurface or a waveform. Thus, the connection portion between eachconductive paste 12 and each electrode terminal 4 is disposed at theconcave part 2 c formed in the bottom step part of the tilt surface 2 b.Accordingly, the connection portion between each conductive paste 12 andeach electrode terminal 4 is separated by a convex part 2 d formed atthe bottom step part of the tilt surface 2 b.

As a result, even when the conductive paste 10 protrudes or expands, theconductive paste is separated by the convex part 2 d. This can preventshort circuit at the adjacent connection portions between the conductivepastes 10 and the electrode terminals 4.

Embodiment 4

FIG. 10 is a conceptual view for illustrating the characteristicstructure of an image display element according to Embodiment 4.

In this embodiment, as shown in FIG. 10, the conductive pastes 10 forconnecting the electrode terminals 4 and the metal film wires 5 arealternately formed at two end parts (tilt surfaces) 2 b and 2 b′ formingthe groove part 3.

The electrode terminals 4 are arranged alternately in correspondencewith the end parts (tilt surfaces) 2 b and 2 b′ in the bottom of thegroove part 3. Namely, at the end part (tilt surface) 2 b of the backpanel 2, the spacing between the adjacent conductive pastes 10 is abouttwice than that in the case of FIG. 5.

Further, in this embodiment, as shown in FIG. 10, there are disposedpits 12 capable of reserving the running down conductive pastes evenwhen a part of the conductive paste 10 runs down to the bottom of thegroove part 3.

Therefore, the spacing between the adjacent conductive pastes 10 becomeslarge. Thus, the width of the conductive pastes 10 can be increased toreduce the electric resistance of the conductive pastes 10 which arewiring parts.

Whereas, the creepage distance between the adjacent conductive pastes 10becomes longer, which inhibits the occurrence of migration. As a result,the insulation reliability between the wires is improved.

Further, the pits 12 are disposed in the bottom of the groove part 3.Therefore, as with the case of Embodiment 2, it is possible to preventthe coated conductive paste having fluidity from protruding or expandingat the bottom of the groove part 3, and thereby causing short circuitbetween the adjacent electrode terminals.

Embodiment 5

FIG. 11 is a conceptual view for illustrating the characteristicstructure of an image display element according to Embodiment 5.

For example, in the structure (FIG. 8) of the image display elementaccording to Embodiment 2 described above, in order to reduce thecontact resistance of the connection part between the electrode terminaland the metal film wire, the width of the conductive paste 10 isincreased to enlarge the pit 12. Accordingly, the area of each partition11 (see FIG. 5) between the adjacent electrode terminals decreases, sothat the bonding strength between the front panel 1 and the back panel 2is weakened.

In order to avoid this, in this embodiment, as shown in FIG. 11, forexample, one pit 12 is divided into three pits 12 a, 12 b, and 12 c as acountermeasure.

Namely, in this embodiment, each pit is divided into a plurality ofparts, and the conductive paste is also divided into a plurality ofparts in correspondence with the divided pits.

This can inhibit the reduction of the area of the partition between theadjacent electrode terminals. As a result, the reliability of the wiringand connection is improved.

Embodiment 6

FIGS. 12A and 12B are each a conceptual view for illustrating thecharacteristic structure of an image display element according toEmbodiment 6.

In this embodiment, as shown in FIGS. 12A and 12B, when the electrodelead-out part is processed, the periphery of the pits 12 shown inEmbodiment 2 described above is filled with a sealing agent 13.Incidentally, FIGS. 12A and 12B show examples of different ways ofcharging the sealing agent 13.

This can improve the strength and reliability of the connection part.

Embodiment 7

In order to illustrate the relationship between the electrode terminals4 and the pixels of the image display element 1 of a large size displayof the invention, a description will be given to a case using an ELdisplay panel as one example of the image display element. This case isan example in which the image display element of FIG. 1 is formed of anEL display panel.

Incidentally, the image display element of the invention is not limitedthereto, and is also applicable to a liquid crystal panel, a PDP, andthe like.

On the front panel 1, a plurality of organic EL elements which arepixels p are arranged to control light emission/non-light emission ofthe pixels (each pixel p of FIG. 6 is one organic EL element). A generalorganic EL element includes a transparent electrode such as ITO, anorganic layer including a hole transport material layer, a lightemission layer, an electron transport layer, and the like, and areflection electrode (e.g., Al), successively formed therein. Thus,light transmits through the transparent electrode from the lightemission layer, and is emitted from the front panel 1 side.

The electrode terminal 4 and the transparent electrode and thereflection electrode are electrically connected, and the electrodeterminal 4 is led out to the groove part 3.

Via the metal film wire 5, (the transparent electrode and the reflectionelectrode) are electrically connected with the connector 6. Thus, acontrol signal indicative of light emission/non-light emission of theorganic EL element is sent from an external driving control circuit.

The electrode terminal may be formed of the same ITO as that of thetransparent electrode. In order to reduce the resistance, the electrodeterminal may be formed of a low resistance metal such as Al, Cr, or Ag.Alternatively, it may be formed of a lamination thereof.

The back panel 2 may be formed of glass as with the front panel 1. Inthe side of the back panel 2 opposite to the organic EL elements, aconcave part is formed with etching, sand blast, or the like. The panels1 and 2 are bonded together so that the concave part-formed side of theback panel 2 and the organic EL elements-formed side of the front panel1 oppose each other.

Both the substrates are sealed and joined by an UV-curable adhesive orthe like. In the sealed space by the concave part, a desiccating agentis set for protection from the deteriorating factors of the organic ELelements such as moisture.

The present invention is useful for implementing an image displayelement capable of undergoing electrode lead-out processing with ease,and capable of inhibiting the occurrence of short circuit of theelectrode lead-out part (connection part between the electrode terminaland the metal film wire).

Various modifications and alterations of this invention will be apparentto those skilled in the art without departing from the scope and spiritof this invention, and it should be understood that this is not limitedto the illustrative embodiments set forth herein.

What is claimed is:
 1. An image display element, comprising: a frontpanel; a back panel opposite to the front panel; a plurality of pixelsarranged in a matrix between the front panel and the back panel, and tobe selected to be in a display or non-display state; and a plurality ofelectrodes for controlling the pixels, the front panel and the backpanel being bonded together with the pixels and the electrodesinterposed therebetween, and the electrodes being connected to a drivingcircuit via metal film wires, wherein the back panel includes a backsurface having a substantially flat end face that is divided such thatelectrode terminals connected to the electrodes are exposed betweenadjacent plural pixel lines, and a groove part having a shape wider atthe top on the back side of the opposing surface from the front panelthan at the bottom is formed at the divided portion of the back surface,the metal film wires are formed on the back side surface of the surfaceof the back panel opposite to the front panel on the substantially flatend face, the electrode terminals and the metal film wires are connectedby a conductive paste coated along a tilt surface forming the groovepart and extended onto the substantially flat end face contacting themetal film wires on the substantially flat end face, and partitions aredisposed between the adjacent electrode terminals at the bottom of thegroove part.
 2. The image display element according to claim 1, whereinthe partitions are formed of a resin material.
 3. The image displayelement according to claim 1, wherein pits are disposed in portions atwhich the conductive pastes are connected to the electrode terminals atthe bottom of the groove part.
 4. The image display element according toclaim 1, wherein concave parts and convex parts are formed at a bottomstep part of the tilt surface forming the groove part, and end parts ofthe conductive pastes connected to the electrode terminals are disposedin the concave parts, and are separated by the convex parts.
 5. Theimage display element according to claim 3, wherein the conductivepastes are formed alternately at two tilt surfaces forming the groovepart.
 6. The image display element according to claim 3, wherein thepits are each divided into a plurality of parts, and the conductivepastes are each also divided in a plurality of lines in correspondencewith the divided pits.
 7. The image display element according to claim3, wherein the periphery of the pits is filled with a sealing agent. 8.The image display element according to claim 5, wherein the periphery ofthe pits is filled with a sealing agent.
 9. The image display elementaccording to claim 6, wherein the periphery of the pits is filled with asealing agent.
 10. A method for manufacturing an image display element,the image display element, comprising: a front panel; a back panelopposite to the front panel; a plurality of pixels arranged in a matrixbetween the front panel and the back panel, and to be selected to be ina display or non-display state; and a plurality of electrodes forcontrolling the pixels, the front panel and the back panel being bondedtogether with the pixels and the electrodes interposed therebetween, andthe electrodes being connected to a driving circuit via metal filmwires, the method, comprising: a first step of dividing a back surfaceof the back panel having a substantially flat end face such thatelectrode terminals connected to the electrodes are exposed betweenadjacent plural pixel lines, and forming a groove part having a shapewider at the top on the back side of the opposing surface from the frontpanel than at the bottom at the divided portion of the back surface; asecond step of forming the metal film wires on the back side surface ofthe surface of the back panel opposite to the front panel on thesubstantially flat end face; a third step of connecting the electrodeterminals and the metal film wires by a conductive paste coated along atilt surface forming the groove part and extended onto the substantiallyflat end face contacting the metal film wires on the substantially flatend face; and a fourth step of disposing partitions between the adjacentelectrode terminals at the bottom of the groove part.
 11. The method formanufacturing an image display element according to claim 10, whereinthe partitions are formed of a resin material.
 12. The method formanufacturing an image display element according to claim 10, whereinpits are disposed in portions at which the conductive pastes areconnected to the electrode terminals at the bottom of the groove part.13. The method for manufacturing an image display element according toclaim 10, wherein concave parts and convex parts are formed at thebottom step part of the tilt surface forming the groove part, and theend parts of the conductive pastes connected to the electrode terminalsare disposed in the concave parts, and are separated by the convexparts.
 14. The method for manufacturing an image display elementaccording to claim 12, wherein the conductive pastes are formedalternately at two tilt surfaces forming the groove part.
 15. The methodfor manufacturing an image display element according to claim 12,wherein the pits are each divided into a plurality of parts, and theconductive pastes are each also divided in a plurality of parts incorrespondence with the divided pits.
 16. The method for manufacturingan image display element according to claim 12, wherein the periphery ofthe pits is filled with a sealing agent.
 17. The method formanufacturing an image display element according to claim 14, whereinthe periphery of the pits is filled with a sealing agent.
 18. The methodfor manufacturing an image display element according to claim 15,wherein the periphery of the pits is filled with a sealing agent.